Influence Of Surface Plastic Deformation On The Propagating Of The Rayleigh Waves

In industrial production, the applied stress and the residual stress often lead to stress corrosion and crack, eventually leading to a shorter service life or a premature failure of engineering structures. The non-destructive ultrasonic testing technique is a potential method in residual stress measurement as it has the outstanding characteristics of harmless to people, non-destructive and online detection. In this investigation, the effect of micro plastic deformation of a tension specimen with certain roughness on the Rayleigh wave propagation was studied. An interesting phenomenon was found that the second acoustoelastic response of a tension specimen was quite different with the first one under the same load which is in the range of linear elasticity. By using finite element simulation, a layer of micro plastic deformation is formed on the surface of the tension specimen because of the local stress concentration around the roughness surface. A basic acoustoelastic test with aluminum and steel compression specimen was carried out and the experimental results reveal that the velocity of the acoustic wave became slower as the plastic strain rate in the measured material was increased. So during the acoustoelastic measurement, we had better polish the surface of the specimens at first, thus keeping the experimental data accurate.